Asthma is a chronic disease and everyone is at risk of developing asthma but the exact cause of asthma is not known. Many factors such as genetic susceptibility, environmental factors, and diet probably contribute to an individual developing this common problem.
- Genetic factors: The exact way or to the extent to which heredity or genetics contribute to the development of asthma is not well understood. But asthma tends to run in families. Children with a family history of asthma are more prone to become hypersensitive to animals, pollens moulds and dust in the environment (genetically predisposed).
- Other allergies: Many people with asthma also have other allergic conditions such as allergic rhinitis and skin allergies. Allergy denotes a hypersensitive response, within the body to certain substances known as allergens.
- Environmental factors: According to hygiene hypothesis, children who are not exposed to bacterial infections (such as children who live in very clean environment) that "kick start" the immune system in early life, are more prone to developing allergies. According to studies, infections early in life may be important in directing the immune system away from allergic responses. Besides this, children from warm, well-furnished, carpeted homes are at risk of asthma (as there is not much airflow and the number of house dust mites in bedding, carpets and furnishings is high).
- Tobacco smoke: Children exposed to tobacco smoke during pregnancy or in early childhood are at higher risk of developing asthma. Their symptoms tend to be more severe.
- Dietary changes: Dietary changes such as eating processed foods, a higher salt intake, a lower antioxidant intake (lack of fresh fruits and vegetables) and a lack of fresh oily fish (lower intake of omega-3 fatty acids) may contribute to the development of asthma. This kind of diet is more prevalent in developed countries and a gradual increase in the prevalence of asthma has been observed in these countries.
- Lack of exercise: People who spend more time in front of the television get far less exercise. Hence their lungs are also not stretched and exercised which makes their airways hypersensitive when exposed to minor irritants.
- Occupational exposure: People who are constantly exposed to irritants in the workplace (such as chemicals, dusts, gases, moulds and pollens) are at higher risk of developing asthma. Professionals from industries such as baking, spray painting of cars, woodworking, chemical production, and farming are at higher risk of developing asthma.
What all people with asthma have in common is airway inflammation which makes them extra sensitive to a number of different trigger factors that can cause bronchoconstriction and bring on asthma symptoms.
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